MixColumns

MixColumns.py

PD = [
 [0x02, 0x03, 0x01, 0x01],
 [0x01, 0x02, 0x03, 0x01],
 [0x01, 0x01, 0x02, 0x03],
 [0x03, 0x01, 0x01, 0x02],
]

def gf3mpy(x, y):                  
 p = 0b100011011
 m = 0
 for _ in range(8):
     m = m << 1
     if m & 0b100000000:
         m = m ^ p
     if y & 0b010000000:
         m = m ^ x
     y = y << 1
 return m

def main(state):
 result = []
 for i in range(4):
     r = []
     p = PD[i]
     for j in range(4):
         s = [state[_][j] for _ in range(4)]
         temp = 0x00
         for k in range(4):
             x, y = p[k], s[k]
             temp ^= gf3mpy(x,y)
         r.append(temp)
     result.append(r)
 return result   


if __name__=="__main__":
 state = [
     [0x33, 0xD2, 0x04,0x96],
     [0xF1, 0xC4, 0xD0,0x0C],
     [0x8C, 0xE7, 0xDE,0x48],
     [0xD3, 0xA4, 0x2C,0xB5],
 ]
 answer = main(state)
 for x in answer:
     for y in x:
         print(hex(y), end=',')
     print()